Lubricating composition and method of making same



E. A. NILL Nov. 28, 1933.

LUBRICATING COMPOSITION AND METHOD OF MAKING SAME Originl Filed nee. 7'. 1927" Patented Nov. 28, 1933 UNITED STATES LUBRICATING COMPOSITION AND DIETHOD OF MAKING SAME Edward A. Nill, Cleveland, Ohio, assignor, by

mesnc assignments, to P. E. Selby, Inc., Cleveland, Ohio, a corporation of Ohio Application December 7, 1927, Serial No. 238,267

Renewed April 22, 1933 12 Claims.

The present invention relates to oil and wax compositions and toy the method of making the same and particularly to compositions of this character suitable for lubricating purposes, the present invention being a continuation in part of my copending application Serial No. 636,639, filed May 4, 1923 now Patent 1,659,149.

In my copending application above referred to, I have disclosed a lubricating composition substantially free from water composed of an analid of a fatty acid and an oil togetherv with a method by which the oil and analid may be directly combined to form a homogeneous compositionand by which, compositions-of different degrees of consistency and lubricating qualities suitable for various uses may be made.

Further investigations which I have made since the filing of the above application have led to the discovery that amids of the fatty acids and other wax-like compounds of fatty acids when combined with oils or Waxes by the method disclosed in the above mentioned application produce results analogous to the results obtained by the use of stearanalid as described in said application, and that not only the simple amid of fatty acids such as stearic, palmitic or arichidic acids may be used, but also aromatic base amids of fatty acids such as toluidines, naphthylamines, etc., and various natural waxes such as carnauba, Montan or candilila wax, beeswax, etc. have the efiect of stiffening the consistency of oils or waxes and of producing lubricating compositions of high lubricating value. Furthermore, I' have discovered that by mixing with an oil a wax-like compound of a fatty acid or a mixture of such compounds selected with reference to their melting points and other physical characteristics, a lubricating composition may be made which has a melting point, a consistency and other physical properties desirable for any one of a great variety of uses.

, It is to be understood that the expression waxlike compounds of fatty acids, as used herein, includes generally the esters and amids of fatty acids which are, in the one case, true waxes, and any other solids which resemble wax, these waxlike compounds being soluble in oils at temperatures above their melting points and acting to stiffen the consistency of the oil.

I have also discovered that when simple amids of fatty acids are employed, a smaller proportion of the amid will suffice to produce a lubricant of a given consistency. These amids of fatty acids have, in general, a melting point which is relatively high as compared to oils and waxes and a relatively small percentage of these amids is I required to solidify an oil to the consistency of grease and lubricating oils of various viscosities can be reduced by the amids to semi-solid or solid consistency. For example, I find'that by combining 5 to 8% of stearamid with 92 to;95% of 28 B. parafline oil, alight colored transparent lubricant is obtained and with 5 to 8% of stearamid and 92 to 95% of cylinder oil, a transparent greenish lubricant is obtained. The former lubricant is suitable for bearings running at high speeds and under light loads while the latter is more suitable for use in bearings which run at low speeds under heavy loads, or for use in ordinary grease cups or high pressure lubricating systems. It is to be understood that the above compositions are merely illustrative, that various oils and wax-like substances may be substituted for the ingredients above mentioned and that the relative proportions of the ingredients may vary widely in different lubricating compositions.

A very important feature of the present invention is the provision of a method of imparting the desired consistency to a. lubricating oil'without the addition of water.

It has been a common practice in the manufacture of lubricating compositions of semi-solid consistency suitable for lubricating various kinds of friction surfaces to add a sufficient quantity of soap to the lubricating oil to give it the desired consistency. In such lubricating compositions, it has been essential to have present a small percentage of water such as 3 or 4% to form an emulsion of. the oil and soap to avoid separation of oil from the relatively large quantity of soap which is usually present in such compositions. The presence of water in the composition is highly disadvantageous since the water evaporates or is lost from the composition due to the heat generated in the bearing in which the composition is used. As the water evaporates, there is a tendency of the oil and soap to separate themselves, permitting the oil, which is of lower viscosity, to seep away from the surfaces which are to be lubricated and the soap, which usually is present in a substantial percentage, forms a gum-like residue, which greatly increases the coefilcient of agent united in a homqgeneouscomp'osition in such manner that they will not separate in service.

In my copending application, Serial No. 227,059, filed October 18, 1927, I have disclosed compositions which, in addition to the oil and stiffening agent, contain quantities of a metallc soap sufficent to raise the melting point of the composition to the desired degree. The addition of the small quantity of soap does not materially affect the method of making the compound and enables me to regulate the melting point as well as the consistency of the compound.

It has also been found that a small percentage of an animal or vegetable oilsuch as lard oil, tallow, cotton seed oil or castor oil mixed with the mineral oil in the composition materially improves the lubricating qualities of the composition, the improvement being presumably due to the property of animal and vegetable oils adhering more firmly to metal at temperatures above normal than mineral oils. For instance, the lubricating qualities of the compositions specifically described above may be materially improved by the addition of approximately 1% of castor oil.

In the accompanying drawing, there is shown one type of apparatus suitable for use in practicing the method of the present invention.

In producing solidified oils by the method of the present invention, the oil, preferably a mineral oil, is thoroughly mixed with a wax-like solidifying agent and with a small percentage of metallic soap, if such soap is used at a temperature above. the melting point of the solidifying agent, and sufliciently high to enable all of the ingredients to mix in liquid form. The liquid mixture is then delivered into a suitable cooling device, which may be of any suitable form capable of rapidly and uniformly cooling the mixture. The liquid mixture is subjected to the cooling operation until the temperature of the mixture has been reduced to a point at which the mixture is in semi-solid condition. The semi-solid mixture may then be delivered into suitable receptacles or containers and allowed to cool slowly to atmospheric temperature. I have found that the rapid and uniform cooling of the mixture is essential to the production of a homogeneous compound.

' Figure l is a vertical section; Fig. 2, a vertical section on the line 2-2 Fig. 1.

The accompanying drawing shows one form of apparatus which may be employed in practicing the process of thepresent invention. A mixing tank 1 is provided in which the oil and stiffening agent may be mixed and this tank is provided with a suitable steam jacket 2, by which the material in the tank may be maintained at the desired temperature. The tank 1- is provided with dicharge outlet 3, which delivers the liquid from the tank onto a cooling roll 4,- through which 6 water is circulated by means of pipes 5 and 6,

the pipe 5 being connected to a water main and the pipe 6 serving as a drain pipe. The liquid discharged onto the cylinder 4 is collected in a trough 7 at one side of the roll which has a bottomv member having its inner'edge contiguous to the surface of the cylinder, and having end plates 8 attached thereto to retain the liquid at the ends of the cylinder. A thin film of the'oily liquid adheres to the-surface of the cylinder as it is rotated past the trough 7 and, during the rotation of the cylinder, this film of liquid israpidly and uniformly cooled to semi-liquid consistency. and is removed from the cylinder by means of a scraper 9, which discharges the semi-solid material into a trough 10 in which i5 mounted a screw conveyor 11. The screw conveyor discharges the material from the trough and agi-' tates the material, keeping .it thoroughly mixed during its passage through the trough. The material is cooled while passing through the trough 10 at a rate slower than on the cylinder 4 and is discharged into a suitable container or receptacle 12, which when filled is removed and allowed to stand for twenty-four hours or longer before sealing. In mixing the ingredients, the stearanilid, stearamid or other wax-like solidifying agent is placed in the botom of the mixing tank 1 and the tank is heated to melt the solidifying agent. If a metallic soap is to be used, this is first added to the solidifying agent and thoroughly incorporated therein by means of a rotating mixer blade 13 within the tank. The mixture in the bottom of the tank is maintained at a predetermined temperature by a steam jacket and the lubricating oil is slowly added and stirred into the mixture in the tank at a rate such that the temperature of the mixture is not materially reduced. When stearanilid or stearamid is used as a solidifying agent, together with a small quantity of metallic soap, the mixture in the mixing tank will be maintained at a temperature of from 250 to 350 F., depending upon the proportions of the ingredients used. After the desired amount of oil has been added in the mixing tank, the discharge outlet is opened and the liquid mixture is permitted to flow to the cooling cylinder. In passing over the cooling cylinder, the temperature of the mixture is lowered to a temperature of approximately 120 and in passing through the discharge trough 10, the temperature of the mixture is lowered to approximately 100, at which temperature the composition may be delivered into suitable containers, which when filled, are allowed to stand for twenty-four hours or longer before the containers are sealed for shipment or before the material in the containers is transferred to other containers for shipment. Y

The process of the present invention makes it possible to produce homogeneous and stable compositions employing metallic soaps which are normally soluble to a very limited degree only in mineral oils, since when mixed with the amids of the fatty acids considerably greater quantities of the soap can be brought into stable solution in the. mineral oil.

The method of the present invention is applicable to the production of the lubricating compositions disclosed in my copending application Serial No. 227,059 abovereferred to. As explained in said application, a very stiff composition may have as low as 8% of mineral oil with the remaining 20% composed of the amid and metallic soap, the amid being in the proportion of 15% or somewhat more, if desired. For

.very stiff compositions such as above referred to,

the temperature of the mixing tank is maintained at a higher temperature than for lighter bodied compositions. For a given composition, the operator may readily determine the temperature between the limits above specified at which the ingredients most rapidly mix and pass into solution.

As set forth in my copending application Serial No..227,059, sodium and calcium, soaps such as stearates increase the melting point of the composition to a marked degree and zinc stearate, while it does not increase the melting point to as great an extent as calcium or sodium soaps, is advantageous for the reason that it doesv not appreciably stifien the consistency and improves the quality of the product by enhancing its smoothness and spreading qualities. A typical example of a lubricant suitable for machines having high speeds and low bearing pressures is:

Zero mineral oil, 91.5%, viscosity 500 Saybolt at F. sodium soap .75%, zinc soap 2.75%, stearanilid 5%.

It will be apparent that the lubricating oil employed in making the composition may be any one of a large number of oils or a mixture of oils and that the solidifying agent may consist of a single wax-like organic compound of a fatty acid or a mixture of-such compounds, and it is to be understood that the term wax-like fatty acid compound" applies to mixtures of such compounds as well as to the individual compounds.

Furthermore, it is to be understood that the particular form of apparatus shown and described, and the particular procedure set forth, are presented for purposes of explanation and illustration and that various modifications of said apparatus and procedure can be made without departing from my invention as defined in the appended claims.

'What I claim is:

l. The herein described method of producing a homogeneous lubricating composition which is,

substantially free from water which consists in mixing with a mineral oil, a stiffening agent in a the form of a wax-like fatty acid compound at a temperature above the melting point of the stiffening agent, and rapidly and uniformly cooling the mixture to a temperature at which the mixture is of semi-solid consistency.

2. The herein described method of producing a homogeneous lubricating composition which is substantially free from. water which consists in mixing with a mineral oil, a stifiening agent in the form of a wax-like fatty acid compound .at a temperature above the melting point of the stiffening agent, rapidly and uniformly cooling the mixture to a temperature at which the mixture is of semi-solid consistency, and slowly cooling the semi-solid mixture to atmospheric temperature.

3. The herein described method of producing a homogeneous lubricating composition which is substantially free from water which consists in mixing with a mineral oil, a stifl'ening agent in-the form of a wax-like fatty acid compound, and a small quantity of'metallic soap at a temperature at which the mixture is in liquid form, and rapidly and uniformly cooling the mixture to a temperature at which the mixture is of semi-solid consistency.

4. The herein described method of producing a homogeneous lubricating composition which is substantially free from water which consists in mixing with a mineral oil, a stiffening agent in. the form of an amid of a fatty acid at a temperature above the melting point of the amid, and rapidly and uniformly cooling the mixture to a temperature at which the mixture is of semi-solid conthe form of an amid of a fatty acid and a relatively small quantity of metallic soap at a temperature at which the mixture is in liquid form, and rapidly and uniformly cooling the mixture to a temperature at which the mixture is of semisolid consistency.

6'. A lubricating composition consisting of a mineral oil having homogeneously combined therewith a stiifening agent, a wax-like organic fatty acid compound, said composition being substantially free from water.

7. A lubricating composition consisting of a mineral oil having homogeneously combined therewith in a relatively small proportion as a stiffening agent, an amid of a fatty acid, said composition being substantially free from water.

8. A lubricating composition consisting of a mineral oil having homogeneously combined therewith as a stiffening agent, stearamid, said composition being substantially free from water.

9. A neutral lubricating composition which is substantially free from water and which consists of paraffine oil having stearamid mixed therewith to stiffen the consistency thereof.

10. A lubricating composition substantially free from water and consisting of mineral oil having a relatively small percentage of animal or vegetable oil mixed therewith and having homogeneously combined therewith as a stiifening agent, a wax-like organic fatty acid compound.

11. A lubricating composition substantially free from water and consisting of mineral oil having a relatively small percentage of animal or vegetable oil mixed therewith and having homogeneously combined therewith as a stiflening agent, a neutral amid of a fatty acid.

12. A lubricating composition substantially free from water and consisting of mineral oil having a small percentage of castor oil mixed therewith and having homogeneously combined therewith, a neutral amid of a fatty acid.

EDWARD A. NILL. 

